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RDMA/cxgb4: DB Drop Recovery for RDMA and LLD queues
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Add module option db_fc_threshold which is the count of active QPs
that trigger automatic db flow control mode.  Automatically transition
to/from flow control mode when the active qp count crosses
db_fc_theshold.

Add more db debugfs stats

On DB DROP event from the LLD, recover all the iwarp queues.

Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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Vipul Pandya authored and Roland Dreier committed May 18, 2012
1 parent 4984037 commit 422eea0
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Showing 4 changed files with 259 additions and 12 deletions.
176 changes: 170 additions & 6 deletions drivers/infiniband/hw/cxgb4/device.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,8 @@ static const struct file_operations stag_debugfs_fops = {
.llseek = default_llseek,
};

static char *db_state_str[] = {"NORMAL", "FLOW_CONTROL", "RECOVERY"};

static int stats_show(struct seq_file *seq, void *v)
{
struct c4iw_dev *dev = seq->private;
Expand All @@ -272,6 +274,9 @@ static int stats_show(struct seq_file *seq, void *v)
seq_printf(seq, " DB FULL: %10llu\n", dev->rdev.stats.db_full);
seq_printf(seq, " DB EMPTY: %10llu\n", dev->rdev.stats.db_empty);
seq_printf(seq, " DB DROP: %10llu\n", dev->rdev.stats.db_drop);
seq_printf(seq, " DB State: %s Transitions %llu\n",
db_state_str[dev->db_state],
dev->rdev.stats.db_state_transitions);
return 0;
}

Expand All @@ -295,6 +300,7 @@ static ssize_t stats_clear(struct file *file, const char __user *buf,
dev->rdev.stats.db_full = 0;
dev->rdev.stats.db_empty = 0;
dev->rdev.stats.db_drop = 0;
dev->rdev.stats.db_state_transitions = 0;
mutex_unlock(&dev->rdev.stats.lock);
return count;
}
Expand Down Expand Up @@ -677,8 +683,11 @@ static int disable_qp_db(int id, void *p, void *data)
static void stop_queues(struct uld_ctx *ctx)
{
spin_lock_irq(&ctx->dev->lock);
ctx->dev->db_state = FLOW_CONTROL;
idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
if (ctx->dev->db_state == NORMAL) {
ctx->dev->rdev.stats.db_state_transitions++;
ctx->dev->db_state = FLOW_CONTROL;
idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
}
spin_unlock_irq(&ctx->dev->lock);
}

Expand All @@ -693,9 +702,165 @@ static int enable_qp_db(int id, void *p, void *data)
static void resume_queues(struct uld_ctx *ctx)
{
spin_lock_irq(&ctx->dev->lock);
ctx->dev->db_state = NORMAL;
idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
if (ctx->dev->qpcnt <= db_fc_threshold &&
ctx->dev->db_state == FLOW_CONTROL) {
ctx->dev->db_state = NORMAL;
ctx->dev->rdev.stats.db_state_transitions++;
idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
}
spin_unlock_irq(&ctx->dev->lock);
}

struct qp_list {
unsigned idx;
struct c4iw_qp **qps;
};

static int add_and_ref_qp(int id, void *p, void *data)
{
struct qp_list *qp_listp = data;
struct c4iw_qp *qp = p;

c4iw_qp_add_ref(&qp->ibqp);
qp_listp->qps[qp_listp->idx++] = qp;
return 0;
}

static int count_qps(int id, void *p, void *data)
{
unsigned *countp = data;
(*countp)++;
return 0;
}

static void deref_qps(struct qp_list qp_list)
{
int idx;

for (idx = 0; idx < qp_list.idx; idx++)
c4iw_qp_rem_ref(&qp_list.qps[idx]->ibqp);
}

static void recover_lost_dbs(struct uld_ctx *ctx, struct qp_list *qp_list)
{
int idx;
int ret;

for (idx = 0; idx < qp_list->idx; idx++) {
struct c4iw_qp *qp = qp_list->qps[idx];

ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
qp->wq.sq.qid,
t4_sq_host_wq_pidx(&qp->wq),
t4_sq_wq_size(&qp->wq));
if (ret) {
printk(KERN_ERR MOD "%s: Fatal error - "
"DB overflow recovery failed - "
"error syncing SQ qid %u\n",
pci_name(ctx->lldi.pdev), qp->wq.sq.qid);
return;
}

ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
qp->wq.rq.qid,
t4_rq_host_wq_pidx(&qp->wq),
t4_rq_wq_size(&qp->wq));

if (ret) {
printk(KERN_ERR MOD "%s: Fatal error - "
"DB overflow recovery failed - "
"error syncing RQ qid %u\n",
pci_name(ctx->lldi.pdev), qp->wq.rq.qid);
return;
}

/* Wait for the dbfifo to drain */
while (cxgb4_dbfifo_count(qp->rhp->rdev.lldi.ports[0], 1) > 0) {
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(usecs_to_jiffies(10));
}
}
}

static void recover_queues(struct uld_ctx *ctx)
{
int count = 0;
struct qp_list qp_list;
int ret;

/* lock out kernel db ringers */
mutex_lock(&ctx->dev->db_mutex);

/* put all queues in to recovery mode */
spin_lock_irq(&ctx->dev->lock);
ctx->dev->db_state = RECOVERY;
ctx->dev->rdev.stats.db_state_transitions++;
idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
spin_unlock_irq(&ctx->dev->lock);

/* slow everybody down */
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(usecs_to_jiffies(1000));

/* Wait for the dbfifo to completely drain. */
while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(usecs_to_jiffies(10));
}

/* flush the SGE contexts */
ret = cxgb4_flush_eq_cache(ctx->dev->rdev.lldi.ports[0]);
if (ret) {
printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
pci_name(ctx->lldi.pdev));
goto out;
}

/* Count active queues so we can build a list of queues to recover */
spin_lock_irq(&ctx->dev->lock);
idr_for_each(&ctx->dev->qpidr, count_qps, &count);

qp_list.qps = kzalloc(count * sizeof *qp_list.qps, GFP_ATOMIC);
if (!qp_list.qps) {
printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
pci_name(ctx->lldi.pdev));
spin_unlock_irq(&ctx->dev->lock);
goto out;
}
qp_list.idx = 0;

/* add and ref each qp so it doesn't get freed */
idr_for_each(&ctx->dev->qpidr, add_and_ref_qp, &qp_list);

spin_unlock_irq(&ctx->dev->lock);

/* now traverse the list in a safe context to recover the db state*/
recover_lost_dbs(ctx, &qp_list);

/* we're almost done! deref the qps and clean up */
deref_qps(qp_list);
kfree(qp_list.qps);

/* Wait for the dbfifo to completely drain again */
while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(usecs_to_jiffies(10));
}

/* resume the queues */
spin_lock_irq(&ctx->dev->lock);
if (ctx->dev->qpcnt > db_fc_threshold)
ctx->dev->db_state = FLOW_CONTROL;
else {
ctx->dev->db_state = NORMAL;
idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
}
ctx->dev->rdev.stats.db_state_transitions++;
spin_unlock_irq(&ctx->dev->lock);

out:
/* start up kernel db ringers again */
mutex_unlock(&ctx->dev->db_mutex);
}

static int c4iw_uld_control(void *handle, enum cxgb4_control control, ...)
Expand All @@ -716,8 +881,7 @@ static int c4iw_uld_control(void *handle, enum cxgb4_control control, ...)
mutex_unlock(&ctx->dev->rdev.stats.lock);
break;
case CXGB4_CONTROL_DB_DROP:
printk(KERN_WARNING MOD "%s: Fatal DB DROP\n",
pci_name(ctx->lldi.pdev));
recover_queues(ctx);
mutex_lock(&ctx->dev->rdev.stats.lock);
ctx->dev->rdev.stats.db_drop++;
mutex_unlock(&ctx->dev->rdev.stats.lock);
Expand Down
24 changes: 21 additions & 3 deletions drivers/infiniband/hw/cxgb4/iw_cxgb4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,7 @@ struct c4iw_stats {
u64 db_full;
u64 db_empty;
u64 db_drop;
u64 db_state_transitions;
};

struct c4iw_rdev {
Expand Down Expand Up @@ -212,6 +213,7 @@ struct c4iw_dev {
struct mutex db_mutex;
struct dentry *debugfs_root;
enum db_state db_state;
int qpcnt;
};

static inline struct c4iw_dev *to_c4iw_dev(struct ib_device *ibdev)
Expand Down Expand Up @@ -271,11 +273,25 @@ static inline int insert_handle_nolock(struct c4iw_dev *rhp, struct idr *idr,
return _insert_handle(rhp, idr, handle, id, 0);
}

static inline void remove_handle(struct c4iw_dev *rhp, struct idr *idr, u32 id)
static inline void _remove_handle(struct c4iw_dev *rhp, struct idr *idr,
u32 id, int lock)
{
spin_lock_irq(&rhp->lock);
if (lock)
spin_lock_irq(&rhp->lock);
idr_remove(idr, id);
spin_unlock_irq(&rhp->lock);
if (lock)
spin_unlock_irq(&rhp->lock);
}

static inline void remove_handle(struct c4iw_dev *rhp, struct idr *idr, u32 id)
{
_remove_handle(rhp, idr, id, 1);
}

static inline void remove_handle_nolock(struct c4iw_dev *rhp,
struct idr *idr, u32 id)
{
_remove_handle(rhp, idr, id, 0);
}

struct c4iw_pd {
Expand Down Expand Up @@ -843,5 +859,7 @@ void c4iw_ev_dispatch(struct c4iw_dev *dev, struct t4_cqe *err_cqe);
extern struct cxgb4_client t4c_client;
extern c4iw_handler_func c4iw_handlers[NUM_CPL_CMDS];
extern int c4iw_max_read_depth;
extern int db_fc_threshold;


#endif
47 changes: 44 additions & 3 deletions drivers/infiniband/hw/cxgb4/qp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,11 @@ static int ocqp_support = 1;
module_param(ocqp_support, int, 0644);
MODULE_PARM_DESC(ocqp_support, "Support on-chip SQs (default=1)");

int db_fc_threshold = 2000;
module_param(db_fc_threshold, int, 0644);
MODULE_PARM_DESC(db_fc_threshold, "QP count/threshold that triggers automatic "
"db flow control mode (default = 2000)");

static void set_state(struct c4iw_qp *qhp, enum c4iw_qp_state state)
{
unsigned long flag;
Expand Down Expand Up @@ -1143,13 +1148,19 @@ static int ring_kernel_db(struct c4iw_qp *qhp, u32 qid, u16 inc)

mutex_lock(&qhp->rhp->db_mutex);
do {
if (cxgb4_dbfifo_count(qhp->rhp->rdev.lldi.ports[0], 1) < 768) {

/*
* The interrupt threshold is dbfifo_int_thresh << 6. So
* make sure we don't cross that and generate an interrupt.
*/
if (cxgb4_dbfifo_count(qhp->rhp->rdev.lldi.ports[0], 1) <
(qhp->rhp->rdev.lldi.dbfifo_int_thresh << 5)) {
writel(V_QID(qid) | V_PIDX(inc), qhp->wq.db);
break;
}
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(usecs_to_jiffies(delay));
delay = min(delay << 1, 200000);
delay = min(delay << 1, 2000);
} while (1);
mutex_unlock(&qhp->rhp->db_mutex);
return 0;
Expand Down Expand Up @@ -1388,6 +1399,14 @@ int c4iw_modify_qp(struct c4iw_dev *rhp, struct c4iw_qp *qhp,
return ret;
}

static int enable_qp_db(int id, void *p, void *data)
{
struct c4iw_qp *qp = p;

t4_enable_wq_db(&qp->wq);
return 0;
}

int c4iw_destroy_qp(struct ib_qp *ib_qp)
{
struct c4iw_dev *rhp;
Expand All @@ -1405,7 +1424,16 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp)
c4iw_modify_qp(rhp, qhp, C4IW_QP_ATTR_NEXT_STATE, &attrs, 0);
wait_event(qhp->wait, !qhp->ep);

remove_handle(rhp, &rhp->qpidr, qhp->wq.sq.qid);
spin_lock_irq(&rhp->lock);
remove_handle_nolock(rhp, &rhp->qpidr, qhp->wq.sq.qid);
rhp->qpcnt--;
BUG_ON(rhp->qpcnt < 0);
if (rhp->qpcnt <= db_fc_threshold && rhp->db_state == FLOW_CONTROL) {
rhp->rdev.stats.db_state_transitions++;
rhp->db_state = NORMAL;
idr_for_each(&rhp->qpidr, enable_qp_db, NULL);
}
spin_unlock_irq(&rhp->lock);
atomic_dec(&qhp->refcnt);
wait_event(qhp->wait, !atomic_read(&qhp->refcnt));

Expand All @@ -1419,6 +1447,14 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp)
return 0;
}

static int disable_qp_db(int id, void *p, void *data)
{
struct c4iw_qp *qp = p;

t4_disable_wq_db(&qp->wq);
return 0;
}

struct ib_qp *c4iw_create_qp(struct ib_pd *pd, struct ib_qp_init_attr *attrs,
struct ib_udata *udata)
{
Expand Down Expand Up @@ -1508,6 +1544,11 @@ struct ib_qp *c4iw_create_qp(struct ib_pd *pd, struct ib_qp_init_attr *attrs,
spin_lock_irq(&rhp->lock);
if (rhp->db_state != NORMAL)
t4_disable_wq_db(&qhp->wq);
if (++rhp->qpcnt > db_fc_threshold && rhp->db_state == NORMAL) {
rhp->rdev.stats.db_state_transitions++;
rhp->db_state = FLOW_CONTROL;
idr_for_each(&rhp->qpidr, disable_qp_db, NULL);
}
ret = insert_handle_nolock(rhp, &rhp->qpidr, qhp, qhp->wq.sq.qid);
spin_unlock_irq(&rhp->lock);
if (ret)
Expand Down
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